1. Field of the Invention
The present invention relates to a knife adapter, and more particularly to a thermal expansion knife adapter with a lowered manufacturing cost.
2. Description of Related Art
With reference to FIGS. 3 and 4, a conventional thermal expansion knife adapter comprises a discal body (30), a shaft connecting sleeve (31) and a knife connecting sleeve (32). The shaft connecting sleeve (31) is conical and is formed on and extends from one side of the body (30). The shaft connecting sleeve (31) has a shaft holding hole defined in the shaft connecting sleeve (31) at an end opposite to the body (30) and is connected to a shaft to make the knife adapter rotating with the shaft. The knife connecting sleeve (32) is conical and is formed on and extends from the other side of the body (30). The knife connecting sleeve (32) has a knife holding hole (33) defined in the knife connecting sleeve (32) at an end opposite to the body (30) and communicating with the shaft holding hole in the shaft connecting sleeve (31).
In use, a knife is inserted into the knife holding hole (33) in the knife connecting sleeve (32), and the knife adapter is heated. With the thermal expansion of the knife connecting sleeve (32), the knife is securely held in the knife holding hole (33) and is rotated with the knife adapter for cutting or turning a working piece. However, to attach and detach different knifes to the knife adapter for different working conditions, the knife adapter has to be heated repeatedly and is always made of an alloy material with a high thermal expansion efficiency, such as alloy steel for hot-forging dies. Therefore, the cost for manufacturing the conventional knife adapter is expensive and high.
To overcome the shortcomings, the present invention tends to provide a knife adapter to mitigate or obviate the aforementioned problems.